Cardiovascular adaptations during sustained acceleration in a short-arm human centrifuge Increases in heart rate, and total peripheral resistance are the main counter-measures during consecutive +g-force exposure

Paper number

IAC-14,A1,2,11,x24788

Author

Mr. Michael Nordine, Charité - University Medicine Berlin, Germany

Coauthor

Mr. Stefan Mendt, Free University of Berlin, Germany

Coauthor

Ms. Katharina Brauns, Germany

Coauthor

Dr. Martina Maggioni, Charité - University Medicine Berlin, Germany

Coauthor

Dr. Alexander Christoph Stahn, Charité - University Medicine Berlin, Germany

Coauthor

Prof. Hanns-Christian Gunga, Charité - University Medicine Berlin, Germany

Coauthor

Dr. Oliver Opatz, Center for Space Medicine Berlin (ZWMB), Germany

Year

2014

Abstract

Introduction The purpose of this investigation was to examine the endogenous physiological cardiovascular counter measures active during 2 rounds of alternating +Gz s in a short arm human centrifuge (SAHC). We hypothesized that the hemodynamic mechanisms at play during initial +Gz, such as increases in heart rate (HR) and total peripheral resistance (TPR), would react to a second +Gz phase profile in the same manner.  
Methods 20 subjects, were exposed to two rounds of +Gz in a SAHC. The G force profile followed a plan of nine phases of varying +Gz exposure. Each subject began with a baseline +0Gz exposure, followed by step by step +Gz phase profile of +1Gz-+2Gz-+1Gz. The second round was identical to the first round of +Gz. Each phase lasted for four minutes. During this experiment, non-invasive cardio-vascular parameters were recorded.   The parameters examined  were cardiac output (CO), heart rate (HR),  mean arterial pressure (MAP),  stroke volume (SV), systolic/diastolic blood pressure (sys/dia BP), and total peripheral resistance (TPR). 
Results From the 20 subjects, 14 successfully completed the entire +Gz profile. In the first round of +Gz, amongst these 14 subjects,HR increased to 34% & TPR to 51% over baseline levels, in order to offset a 28% decrease in CO. In the second round of +Gz, HR & TPR increased to over 35% and 45% over baseline respectively, whereas CO decreased to 32% below baseline.  
Discussion The results from this study showed  that the physiological counter-measures active during a first exposure to +Gz are just as active in a subsequent second exposure to +Gz.

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IAC-14,A1,2,11,x24788.brief.pdf

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